I'm looking for the perfect lens that would best serve my purpose on mostly landscape and portrait pictures with a $300 budget that couldn't possible nudge to a higher amount. Basically I'm looking for an all around lens for my one and only.

I am currently using a Canon Rebel XT with a 28-80 f3.5-5.6 Tamron lens I borrowed from my cousin. I kind of like the zoom range on that one but if it would be possible I'd go for one that's a little wider and maybe even more zoom. And since my budget is so tight it would probably be OK if it were a Tamron or sigma lens. And I am more interested in quality glass for the money than an f2.8 aperture.:-)

It sounds like you want something starting out wider than 28mm and going longer than 80mm. Yet, you want higher quality and under $300.

That's s tall order...

Something like the Canon 24-85mm f/3.5-4.5 would be about right budget wise. But, you may want to have something starting out wider.

Something like a Canon 17-85mm f/4-5.6 IS would start out even wider (but, it's running in the $500s now).

There are a number of other popular zooms starting out at around 17 or 18mm. But, most will not go as long as you seem to want ("more zoom" compared to the 28-80mm you tried).

But, your wish for higher quality would be a concern. Anytime you have more focal range from wide to long, the manufacturers tend to make some design compromises. So, lenses with a less ambitious focal range will sometimes offer higher quality images.

There are many other choices (but, not many are going to start out wider and go longer than the lens you're looking at if you want good quality). You can even get ultra zoom lenses like a Tamron 18-250mm. But, these types of lenses have their drawbacks.

Perhaps some of our Canon shooters will have some suggestions and can give you pros and cons of some of the available choices.